qspinlock.h

 1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef _ASM_LOONGARCH_QSPINLOCK_H
 3#define _ASM_LOONGARCH_QSPINLOCK_H
 4
 5#include <linux/jump_label.h>
 6
 7#ifdef CONFIG_PARAVIRT
 8
 9DECLARE_STATIC_KEY_FALSE(virt_spin_lock_key);
10
11#define virt_spin_lock virt_spin_lock
12
13static inline bool virt_spin_lock(struct qspinlock *lock)
14{
15	int val;
16
17	if (!static_branch_unlikely(&virt_spin_lock_key))
18		return false;
19
20	/*
21	 * On hypervisors without PARAVIRT_SPINLOCKS support we fall
22	 * back to a Test-and-Set spinlock, because fair locks have
23	 * horrible lock 'holder' preemption issues.
24	 */
25
26__retry:
27	val = atomic_read(&lock->val);
28
29	if (val || !atomic_try_cmpxchg(&lock->val, &val, _Q_LOCKED_VAL)) {
30		cpu_relax();
31		goto __retry;
32	}
33
34	return true;
35}
36
37#endif /* CONFIG_PARAVIRT */
38
39#include <asm-generic/qspinlock.h>
40
41#endif // _ASM_LOONGARCH_QSPINLOCK_H